Flame retardant fiber blend

ABSTRACT

There is provided a flame retardant fiber blend which is especially useful for children&#39;&#39;s sleepwear. This blend is comprised of from about 10 to about 90 percent (by weight of blend) of polyester fiber and at least 10 percent (by weight of blend) of a flame-retardant acetate fiber which is comprised of from about 0.5 to about 25 percent (by weight of acetate fiber) of at least one tris(polyhaloaliphatic) phosphate.

United States Patent Mayer 1 1 Dec. 10, 1974 [5 1 FLAME RETARDANT FIBERBLEND 3,744,534 7/1973 Henry et a] 57/140 BY x [75] Inventor: MichaelDainis Mayer, Charlotte,

N.C. Primary Examiner-John Petrakes [73] Assignee: Celanese Corporation,New York, Attorney Agent or Firm-Thomas Morgan [22] Filed: Dec. 10, 1971[57] ABSTRACT Appl. No.: 206,852

US. Cl 57/140 BY, 161/169 Int. Cl D02g 3/04, D02g 3/44 Field ofSearch.... 57/140 R, 140 BY; 161/169, 161/170, 168

References Cited UNITED STATES PATENTS 5/1973 Feller 57/140 R 8 Claims,N0 Drawings FLAME RETARDANT FIBER BLEND This application relates to anovel fiber blend which is useful for the preparation of flame-retardantchildrens sleepwear.

The childrens sleepwear market is currently dominated by 100 percentcotton fabric sleepers and by nylon/acetate and nylon/triacetate nappedtricot fabrics for nightgowns; the aforementioned fabrics are veryflammable.

Because of possible danger to young children in wearing flammablesleepwear, the Secretary of Commerce recently issued the ChildrensSleepwear Standard for the Flammability of Childrens Sleepwear (DOC FF3-71, issued July 27, 1971). This standard, which covers any product ofwearing apparel up to and including size 6X ...intended to be wornprimarily for sleeping or activities related to sleeping..., sets fortha test via which one can determine whether any specified piece ofwearing apparel will meet acceptance according to the standard.

There thus is a vital commercial need for childrens sleepwear which willpass the aforementioned test. Accordingly, it is an object of thisinvention to provide a fiber-blend which can be used to makeflame-retardant childrens sleepwear.

In accordance with this invention, there is provided a flame-retardantfiber-blend comprised of at least 10 weight percent (by weight of blend)of flame-retardant acetate fiber and from about 10 to about 90 weightpercent (by weight of blend) of polyester fiber, wherein:

1. said flame-retardant acetate fiber is comprised of from about 0.5 toabout 25 weight percent of at least one tris(polyhaloaliphatic)phosphate containing from about 3 to about 24 carbon atoms, and

2. at least 90 weight percent of the remainder of the fiber-formingmaterial in said blend (i.e., the material which is not flame-retardantacetate) consists of polyester.

The term acetate" as used herein refers to a fiber in which thefiber-forming substance is cellulose acetate, and this term is genericto both primary and secondary acetate. Cellulose triacetate (primaryacetate) is a cellulose ,ester having less than 0.29 free hydroxylgroups per anhydroglucose unit and an acetyl value of at least about 60percent; another definition which may be used in that primary acetate iscellulose acetate wherein not less than 92 percent of the hydroxylgroups are acetylated. Secondary acetate fibers are generally consideredto be those having an acetyl value of less than 59 percent, moreparticularly between about 50 to about 58 weight percent calculated asacetic acid.

The acetate fibers used in this invention are flame retarded by theinclusion therein of from about 0.5 to about 25 percent (by weight ofacetate fiber) of at least one tris(polyhaloaliphatic) phosphate. It ispreferred that the acetate fiber be comprised of from about 3 to about18 weight percent of said phosphate, and it is even more preferred thatfrom about 3 to about 10 weight percent be used. in the most preferredembodiment, from about 3.5 to about 7 weight percent of said phosphatecomprises the acetate fibers used in this invention.

The prior art discloses some of the flame-retardant acetate fibers usedin this invention. Reference may be had, e.g., to British Pat. Nos.973,355 and 958,120, the disclosures of which are hereby incorporated byreference.

It is preferred that the tris(polyhaloaliphatic) phosphate contain fromabout 3 to about 24 carbon atoms, and it is even more preferred that itcontain from about 2 to about 8 carbon atoms. The halogen substituentson the phosphate may be bromine. Thus, e.g., some preferred phosphatesinclude, e.g., tris(dibromoethyl) phosphate, tris(tribromomethyl)phosphate, tris(dibromoethyl) phosphate, tris(tribromoethyl) phosphate,tris(tetrabromoethyl) phosphate, tris(pentabromoethyl) phosphate, tris(dibromopropyl) phosphate, tris(tribromopropyl) phosphate,tris(tetrabromopropyl) phosphate, tris(pentabromopropyl) phosphate,tris(hexabromopropyl) phosphate, tris(heptabromopropyl) phosphate,tris(dibromobutyl) phosphate, tris(tribromoheptyl) phosphate,tris(tetrabromooctyl) phosphate, and the like. Alternatively, thephosphate may be substituted by both bromine and chlorine (subject tothe limitation that there is at least one bromine substituent on each ofthe alkyl groups of the phosphate); tris(1-bromo-3-chloroisopropyl)phosphate, e.g., works especially well. The most preferred phosphate isselected from the group consisting of tris(2,3-dibromopropyl) phosphateand tris(l-bromo- 3-chloroisopropyl) phosphate.

When the flame-retardant acetate fiber used in this invention isfiber-blended with other fibers, the resulting fiber-blends generallyfail the test set forth in Children's Sleepwear Standard DOC FF 3-7l.Thus, e.g., when 35 per cent (by weight of fiber blend) of flameretardant acetate is fiber-blended with either regular acetate fiber(which does not contain the aforementioned phosphate), nylon fiber,modacrylic fiber, acrylic fiber, flame-retardant rayon fiber, rayonfiber, or cotton fiber, each of the fiber-blends produced fails theaforementioned flammability test. Polyester fiber is not inherently moreinflammable than, e.g., nylon fiber, and thus it is very unexpected andsurprising that a fiber-blend of flame-retardant acetate fiber withpolyester fiber passes said flammability test.

A textile article comprised solely of flame-retardant acetate will passthe aforementioned flammability test; however for many uses it will notpossess satisfactory strength or aesthetic properties. Textile articlesmade from the fiber-blend of this invention, however, areself-extinguishing (and pass the flammability test) and have improvedaesthetics and durability; moreover they are more economical thanfabrics consisting of only flame-retardant acetate or flame-retardantpolyester.

The fiber-blend of this invention is comprised of at least 10 percent(by weight of blend) of flameretardant acetate fiber. It is preferredthat it be comprised of at least 25 percent (by weight of blend) offlame-retardant acetate fiber, and it is most preferred that it becomprised of at least 50 weight percent of such acetate fiber. At least90 percent (by weight of blend) of the remainder of the fiber in saidfiber blend consists essentially of polyester fiber; it is preferredthat all of the remainder of the fiber in the fiber blend consistessentially of polyester fiber. As used herein, the term polyesterrefers to a manufactured fiber in which the fiber-forming substance isany long chain synthetic polymer composed of at least percent by weightof an ester of a dihydric alcohol and terephwherein n is from 2 to 10(preferably n is 2 to 4 and most preferably n is 2).

Textile articles made from the fiber-blend of this invention areself-extinguishing," i.e., they are fire resistant to the extent thatonce an igniting flame has ceased to contact unburned parts of thetextile structure the article has the inherent ability to resist furtherpropagation of the flame along its unburned portion, thereby stoppingthe internal burning process. Recognized tests to determine whether atextile article is selfextinguishing include, inter alia, the AmericanAssociation of Textile Chemists and Colorists Test Method 34-1966 andthe National Bureau of Standards Test described in DOC FF 3-71.

The term blend" as used herein refers to both mixtures (wherein two ormore types of staple, e.g., are combined so that the components remainvisually distinct from each other on close examination) and blends(wherein the fibers are combined so intimately that in the final yarn orfabric it is difficult to distinguish the component fibers). Thefiber-blend of this invention may be prepared by any of several methodswell known to the textile art. Thus, e.g., fiber-blending prior totextile processing or draw-frame-blending of sliver stock may be used.Thus, e.g., a wet lay process may be used. Thus, e.g., a process whereintwo or more beams of filament or staple yarn are employed to prepare atricot fabric may be used. Nay, any process which provides a textilestructure (such as a yarn or a fabric) with the specified combination offiber types will provide a fiber blend" within the meaning of thisinvention and may be employed.

It is understood that, although not necessary to the present invention,the polyester component of the fiber-blend may also contain a flameretardant additive.

Char Length (5.5" max.)

weight percent of flame-retardant acetate.

The fabric was washed, rinsed, and then subjected to the AATCC-34-66Vertical Flammability Test (no glass thread); its performance is shownbelow:

Course direction Wale direction Burn Time (2 sec. max.)

() Glow Time (2 sec. max.) 0

This fabric is superior to the best prior art childrens sleepwearfabric. Prior to this invention, the only way to produce cellulosicsleepwear fabrics which were flame retardant was to treat these fabricswith a flame retardant finish; this finish treatment is expensive, has alimited durability to washing, and renders treated cotton fabrics weakand stiff. The fabric of this invention is superior to cotton fabricstreated with a flame retardant finish inasmuch as the former has goodaesthetics, superior fabric strength, permanence to washing, drycleaning, and bleaching, and is neither toxic nor irritating to theskin; furthermore the former is cheaper than the latter.

Example 2 A spun single knit jersey fabric with a density of 6 ouncesper square yard was produced from a 50/50 polyethyleneterephthalate/flame-retardant acetate 10/1 cc spun yarn; the flameretardant acetate was comprised of 4 weight percent of tris(2,3-

f dibromopropylphosphate). This fabric passed AATCC test 34-66, having aWale direction burn time of 0 seconds, a glow time ofO seconds, and achar length of 3.5 inches. Example 3 The following fiber blends (yarns)were prepared from 3 denier per filament 1.5 inch flame-retardant ac- 0etate staple (which is comprised of4 weight percent oftris(2,3-dibromopropylphosphate) and polyester.

Percent Flame I Retardant Acetate Percent Specified Polyester PolyesterUsed 10 2.25 d.p.f. 1.5" polyester 25 2.25 d.p.f. l 5" polyester 25 L5d.p.f. l 5" polyester 35 2.25 d.p.f l 5" polyester 35 2.25 d.p.f. 1.5"polyester 2.25 d.p.f. l.5" polyester 50 L5 d.p.f. 1.5 polyester In orderto better illustrate their invention, applicants present the followingexamples which are not to be deemed limitative of their invention.Unless otherwise stated, all parts are by weight and all temperaturesare in degrees centigrade.

EXAMPLES Example 1 A napped tricot fabric with a density of 2.5 ouncesper square yard was knitted with ajersey stitch from 40 denierpolyethylene terephthalate (back bar) and denier acetate which wascomprised of 4 weight percent of tris-(2,3-dibromopropyl-phosphate);this fabric was comprised of 33 weight percent of polyester and 67 Ineach of the above cases, the polyester used was poly (ethyleneterephthalate). When 6 ounce/square yard jersey fabrics produced fromeach of the aforementioned yarns lO/l cc spun yarn) are tested by thechildrens sleepwear standard test, the fabrics pass the test,

I having a char length of from 1.5 to 2.5 inches and no Example 6 Thefollowing fiber blends were made from 3.0 d.p.f. 2 inch flame-retardantacetate staple (comprised of 4 weight percent oftris-2,3-dibromopropylphosphate) and modacrylic (Dynel):

Percent of Specified Modacrylic Percent Flame Modacrylic Used RetardantAcetate 90 3.0 d.p.f. 2" 75 25 3.0 d.p.f. x 2" 65 35 3.0 d.p.f. 2" 50 503.0 d.p.f. x 2'' Each of these blends when made into a jersey fabricwith a density of 6 ounces/square yard burned the entire length of thefabric when tested in accordance with AATCC 34-66. It is noteworthy thatfabrics made from either 100 percent of modacrylic or 100 percent offlame-retardant acetate pass the AATCC 34-66 test.

Example 7 A blanket sleeper fabric with a density of 10 ounces/- squareyard was made from a polyester/flame-retardant acetate/acrylic blend.The back yarn was 16/] cc 50/50 1.5 d.p.f. X 1.5 inch polyester/3.0d.p.f. X 1.5 inch flame-retardant acetate. The face yarn was 50/50 3.0d.p.f. 2 inch modacrylic/3.0 d.p.f. 2.0 flame-retardant acetate. Thisthree way blend fabric burned when tested by AATCC 34-66 and failed thetest.

A blanket sleeper with a density of 10 ounces/square yard was made withthe back yarn described above but with a face yarn of 100 percent 3.0d.p.f. 2 inch flameretardant acetate. It passed the aforementioned AATCCtest.

Example 8 When, in substantial accordance with Example 1,flame-retardant acetate and flame retardant rayon (the latter containingabout 20 weight percent of tris[2,3- dibromopropyl] phosphate) wereblended in dry lay non-woven fabrics and tested by AATCC 34-66, thefabrics failed the test..

Example 9 An 80/20 tricot fabric with a density of 2.5 ounces/- squareyard produced using 80 percent of 55 denier flame-retardant acetate onthe face of the fabric and 20 percent of 15 denier nylon 6.6 yarn on theback of the fabric was produced. This fabric was not selfextinguishingand thus failed the AATCC 34-66 test.

As used herein, the term fiber-blend refers to staple blends, filamentblends, fabrics, and the like. Thus, e.g., a doubleknit fabric comprisedof the specified amounts of flame-retardant acetate fiber and polyesterfiber is within the scope of this invention. A dou bleknit fabriccomprised of at least 30 weight percent of yarn ends composed of a blendof polyester and flameretardant acetate also is within scope of thisinvention. In said fabric it is preferred that the polyester and acetateyarns be continuous filament yarns of opposite torque which are randomlyintermingled.

Although the above examples and descriptions of this invention have beenvery specifically illustrated, many other modifications will suggestthemselves to those skilled in the art upon a reading of thisdisclosure; these are intended to be comprehended within the scope ofthis invention.

What is claimed is:

l. A flame-retardant fiber-blend comprised of at least 10 weight percent(by weight of blend) of flameretardant acetate fiber and from about 10to about weight percent (by weight of blend) of polyester fibers,wherein:

a. said flame-retardant acetate fiber is comprised of from about 0.5 toabout 25 weight percent of at least one tris(polyhaloaliphatic)phosphate containing from about 3 to about 24 carbon atoms, and

b. said polyester fiber comprises at least 90 weight percent of thenon-flame-retardant acetate fibers of the blend.

2. The fiber-blend of claim 1, wherein:

a. said flame-retardant acetate is comprised of from about 3 to about l8weight percent of said phosphate,

b. said polyester is poly(ethylene terephthalate), and

c. at least about 25 percent of said fiber blend is comprised of saidflame-retardant acetate fiber.

3. The fiber-blend of claim 2, wherein said phosphate istris(dibromopropyl) phosphate and said acetate fiber is comprised of upto about 10 weight percent of said phosphate.

4. The fiber-blend of claim 3, wherein said phosphate is tris(2,3-dibromopropyl) phosphate and said phosphate comprises from about3.5 to about 7 weight percent of said flame-retardant acetate fiber.

5. The fiber-blend of claim 2, wherein said phosphate is tris(l-bromo-3-chloroisopropyl) phosphate and said acetate fiber is comprisedof up to about 10 weight percent of said phosphate.

6. A doubleknit fabric of enhanced flame resistance comprising aneffective proportion of at least 30 weight percent of yarn ends composedof the fiber-blend of claim 1.

7. The fabric of claim 6, wherein said yarn ends comprise a false twisttextured continuous filament poly- (ethylene terephthalate) yarnrandomly intermingled with at least 10 weight percent (by weight of yarnends) of a false twist textured, continuous filament, flameretardantacetate yarn, said acetate yarn being comprised of from about 0.5 toabout 25 weight percent of at least one tris(polyhaloaliphatic)phosphate.

8. The fabric of claim 7, wherein said false twist textured yarns are ofopposite torque.

1. A FLAME-RETARDANT FIBER-BLEND COMPRISED OF AT LEAST 10 WEIGHT PERCENT(BY WEIGHT OF BLEND) OF FLAME-RETARDANT ACETATE FIBER AND FROM ABOUT 10TO ABOUT 90 WEIGHT PERCENT BY WEIGHT OF BLEND) OF POLYESTER FIBERS,WHEREIN: A. SAID FLAME-RETARDANT ACETATE FIBER IS COMPRISED OF FROMABOUT 0.5 TO ABOUT 25 WEIGHT PERCENT OF AT LEAST ONETRIS(POLYHALOALIPHATIC) PHOSPHATE CONTAINING FROM ABOUT 3 TO ABOUT 24CARBON ATOMS, AND B. SAID POLYESTER FIBER COMPRISES AT LEAST 90 WEIGHTPERCENT OF THE NON-FLAME-RETARDANT ACETATE FIBERS OF THE BLEND.
 2. Thefiber-blend of claim 1, wherein: a. said flame-retardant acetate iscomprised of from about 3 to about 18 weight percent of said phosphate,b. said polyester is poly(ethylene terephthalate), and c. at least about25 percent of said fiber blend is comprised of said flame-retardantacetate fiber.
 3. The fiber-blend of claim 2, wherein said phosphate istris(dibromopropyl) phosphate and said acetate fiber is comprised of upto about 10 weight percent of said phosphate.
 4. The fiber-blend ofclaim 3, wherein said phosphate is tris (2,3-dibromopropyl) phosphateand said phosphate comprises from about 3.5 to about 7 weight percent ofsaid flame-retardant acetate fiber.
 5. The fiber-blend of claim 2,wherein said phosphate is tris(1-bromo-3-chloroisopropyl) phosphate andsaid acetate fiber is comprised of up to about 10 weight percent of saidphosphate.
 6. A doubleknit fabric of enhanced flame resistancecomprising an effective proportion of at least 30 weight percent of yarnends composed of the fiber-blend of claim
 1. 7. The fabric of claim 6,wherein said yarn ends comprise a false twist textured continuousfilament poly(ethylene terephthalate) yarn randomly intermingled with atleast 10 weight percent (by weight of yarn ends) of a false twisttextured, continuous filament, flame-retardant acetate yarn, saidacetate yarn being comprised of from about 0.5 to about 25 weightpercent of at least one tris(polyhaloaliphatic) phosphate.
 8. The fabricof claim 7, wherein said false twist textured yarns are of oppositetorque.